Tech: CFM Engine Breathers

Breathe Easy

With a CFM Performance engine breather, your Ford can let off pressure

By Steve Turner

If you’ve been around race cars, you know they are always equipped with crankcase breathers to relieve the pressure that builds up inside the engine. However, you don’t often see breathers on modern cars because they are equipped with sensitive emissions equipment, so adding one might throw a code. Worse yet, an unmetered leak on the engine could cause a dangerous lean condition.

CFM Performance offers a unique breather that is compatible with modern PCV systems. It won’t cause an unmetered leak or a check-engine light, but it will allow your crankcase to cast out excess pressure. They look pretty sharp too, and they are available in chrome, flat black, gloss black, hydrocarbon, wrinkle black, wrinkle blue, wrinkle red, and silver vein finishes. This is the chrome version for Shelby GT500s (PN 1-1010; $74.95).

Now, if you have a Ford with forced induction, it’s likely that the crankcase builds a lot of pressure under boost. This can lead to blow-by, which is cylinder pressure making it past the rings and into the crankcase. Since the stock positive crankcase ventilation system only works with vacuum at idle and part throttle, there really is no escape for the pressure when you are driving hard.

Even if your engine was born with boost, it’s highly likely you have increased the boost level over what the stock system was designed to handle. Fortunately the clever folks at CFM Performance have developed a breather that is compatible with modern engines. It allows the factory PCV system to function properly. Moreover, the CFM breathers won’t trip any lights on your dash or cause any lean conditions.

If you’ve ever seen breathers on race cars, you often see the filters wrapped in rags to keep the oil pushing out of the filter from dripping onto the engine and causing bad things. Well, that isn’t a concern with the CFM Performance breather, as it features an internal baffle to keep the oil away from the filter element.

We first learned about these clever units when we gave one away as the prize for our regular caption contest. Having learned a bit about them, we decided the breathers were worth further examination. As such, your author ordered up a pair for two unique but boosted project cars—Project Silver Lining, a 2013 Focus ST, and Project Vapor Trail, a 2008 Shelby GT500.

Since the Focus ST is a driver, I started it up and removed the stock oil filler cap while it ran. I could feel a significant amount of pressure pushing out of the filler opening. Moreover, little drops of oil splashed out. Clearly it’s not a good idea to remove the cap with the engine running, but it did show the breather would relieve some pressure, which is even higher under boost. Moreover, the oil drops proved the baffle was essential. Check out the install here:

Both cars are fed with well-beyond-stock boost levels, so the CFM breathers seemed like good idea. If you think your ride might benefit from one as well, don’t fret. CFM also offers fitments for 1986-2014 Ford Mustangs, 1999-2004 Lightnings, 2003-2004 Harley F-150s, and other Fords.

I run a CFM breather on my blown 3v. Deleted the PCV, put on the CFM and got some oil weepage from pressure build up. Hooked the PCV catch can back up, still using the CFM oil fill breather and everything is good again.